The state of the art may be defined by the following patents:
FR-A-2,636,832: This implant is constituted by a truncated conical piece on the external surface of revolution of which is provided a conical threading and having a truncated conical axial bore opening at its large end and adapted to receive a truncated conical pivot of complementary shape secured to the prosthesis in question, means being provided for permitting the screwing of this implant into a recess first drilled and tapped in the bone of the jaw of the patient for which this prosthesis is destined.
FR-A-2,634,369: Its first element is in the shape of a spiral hollowed out by a central recess surmounted by a marginal base which positions itself at the level of the gums and whose diameter is calculated to receive both a false root and the prosthetic tooth which is supported by this latter without extending beyond said base.
FR-A-2,610,191: The intraossious implant according to the invention is constituted by a cylindrical body adapted to be emplaced in a well drilled in a bony wall after opening the soft tissues, the cylindrical body being provided with an axial recess adapted to receive a closure member after the positioning of the implant and before closing of the soft tissues and said axial recess receiving after removal of the closure member a root which carries the prosthesis. The implant according to the invention is characterized in that it is provided at the upper part of its body and in prolongation of this latter with at least one thin perforated wall.
EP-0 126 624: A fixed dental implant adapted for the jaw, comprising two connected members, one being provided with external screw threads to be screwed into the jaw and a central hole about an axis in which one end of the other part which bears a dental prosthesis is introduced. A closure is provided in the first part, the second part being introduced into the first, such that the grooves extend beyond and coact with the closure to permit a certain axial movement, as in a natural tooth. A supplemental closure is provided between the opposed surfaces of the first part and the prosthesis to give a shock absorbing effect. Hooks are provided to facilitate removal of the implant if necessary.
GB-2 210 795: The buccal implant has the shape of a cylinder comprising a flat proximal end and a rounded distal end. Projecting portions are formed on the cylindrical surface and are inclined from the proximal end of the cylindrical body toward its distal end. The projecting portions are radially spaced and grooves are provided on the inclined surface. A lateral perforation hole is provided in the distal end of the cylindrical body. The proximal end comprises a recess of hexagonal shape for the reception of a tool permitting exerting torsion.
Application to the provision of foundations for dental prostheses.
DE-U-8903050.8: Screwable implant for the securement of a dental prosthesis, with a screw-threaded portion adapted to be screwed into a jaw and with an occlusal support pillar which comprises a head, a neck as well as axially internal screw threading, characterized by the fact that the screw-threaded part is provided with a diameter regularly increasing from its free end, that between the neck and the free end, it is provided with channeling parallel to the axis, and that in the passage between the neck of generally cylindrical form and the head provided with a periphery of external polygonal shape, is provided a shoulder whose diameter is greater than that of the neck and of the head.
DE-U-9001596.7: Cylindrical self-tapping screw implant characterized by the fact that:
1. the entirely cylindrical part (about 1/4 of the total length) comprises a tapped hole with an engagement chamfer and two diametrically opposed recesses for the insertion by screwing of different intrabuccal elements, or for the engagement of a tool for screwing it in
2. the entirely cylindrical part is smooth and polished and the screw element which follows it is rough or polished
3. the screw shaped part (about 3/4 of the total length) as concerns the elements constituting the threading, becomes slightly thinner toward the base, but the hub, of smaller diameter, becomes thinner more abruptly
4. the end of the screw is rounded and is not self-drilling
5. the screw-shaped portion comprises two longitudinal grooves reamed also in the body of the hub, disposed obliquely relative to the longitudinal axis
6. the turns of the threading thus interrupted are sharpened at their forward end (in the direction of rotation corresponding to screwing).
The implant according to the invention is the only cylindrical and/or cylindro conical implant for axial insertion adapted to possess all of the properties necessary to be emplaced according to one or several of the four modes previously described. In other systems, only one mode is generally possible, two at the most. This is why most of the systems propose several embodiments to permit the implant to be adapted to the various categories of bone.
British patent 2 210 795 describes two types of implant: a first with the vertical striations parallel to the longitudinal axis of the implant (see FIG. 12) and a second with horizontal striations parallel to the longitudinal axis of the implant (see FIG. 1).